This invention relates to a webbing lock device for locking as necessary an occupant restraining webbing used in a seatbelt system for protecting an occupant in the event of an emergency situation of a vehicle, and particularly to a webbing lock device wherein the intermediate portion of the webbing is directly clamped to lock the webbing, whereby the occupant is brought into a restrained state.
In an ordinary webbing retractor used in a seatbelt system, even after the webbing unwinding rotation of a takeup shaft is locked, the condition of loosely wound webbing takes place, thus causing to unwind a considerable length of the webbing. To overcome this disadvantage, there has been proposed a webbing lock device wherein, when the tension of the webbing is increased, the increased webbing tension is utilized to directly clamp and lock the intermediate portion of the webbing.
In this webbing lock device, a pair of clamp members are caused to approach each other by the webbing tension in the event of an emergency situation of the vehicle, whereby the webbing is clamped between the clamp members to be prevented from moving in the longitudinal direction thereof, thereby enabling to restrain the occupant.
However, with the conventional webbing lock device of the type described, the force of clamping the webbing by the pair of clamp members increases in proportion to the webbing tension, and consequently, when the webbing tension has increased to an extreme extent, the clamping force increased in proportion to the webbing tension presses the intermediate portion of the webbing beyond necessity, thereby possibly causing damages to the webbing.
The present invention has been developed to obviate the abovedescribed disadvantages of the prior art and has as its object the provision of a webbing lock device wherein, even when the webbing tension increases to an extreme extent, the clamp members do not cause damages to the intermediate portion of the webbing.
In the webbing lock device according to the present invention, a deformable member is provided between a contact portion on which the webbing is wound and the clamp members, and, when the webbing tension exceeds a predetermined value, the force of clamping the webbing is restricted by the deformation of the deformable member.